Variable angle orthopedic fasteners for fixation of an orthopedic implant

Abstract

Systems for variable angle insertion of surgical fasteners relative to an orthopedic plate with locking of the surgical fastener relative to the plate upon insertion. The systems may include a pivot member secured relative to either the orthopedic plate or the fastener. In either regard, the pivot member may provide locking engagement with the plate to lockingly engage the fastener relative to the plate.

What is claimed is: 
     
       1. An orthopedic system for fixation of an orthopedic plate to a bone of a patient, comprising:
 a plate body extending between an upper surface and a lower surface of the plate body; 
 an aperture extending through the plate body from the upper surface to the lower surface along a reference axis, the aperture having a sidewall extending circumferentially about an interior of the aperture; 
 a pivot member retained within the aperture, the pivot member comprising an outer surface corresponding to the sidewall, the pivot member defining a bore extending along a fastener insertion axis, wherein the pivot member is rotationally fixed in the aperture around the reference axis yet is displaceable relative to the plate body within the aperture to define an included angle between the reference axis and the fastener insertion axis; and 
 a fastener comprising an elongate portion and a head portion, wherein the elongate portion extends along the fastener insertion axis defined by the pivot member bore and the head portion is engaged with the pivot member to radially expand the pivot member to frictionally engage the sidewall with the outer surface to restrict displacement of the pivot member within the aperture relative to the plate body, 
 wherein the plate body comprises extensions adjacent to the upper surface and extending relative to the aperture, wherein the extensions extend relative to the aperture to retain the pivot member in the aperture. 
 
     
     
       2. The orthopedic system of  claim 1 , wherein the extensions are displaceable into position to extend relative to the aperture upon receipt of the pivot member into the aperture to secure the pivot member within the aperture. 
     
     
       3. The orthopedic system of  claim 1 , wherein at least one of the bore or the head portion of the fastener disposed within the bore comprises a sloped surface such that the head portion and the bore are engageable upon receipt of the fastener in the bore to cause the pivot member to radially expand. 
     
     
       4. The orthopedic system of  claim 3 , wherein the pivot member comprises an expansion slot that allows for expansion of the pivot member radially relative to the fastener insertion axis. 
     
     
       5. The orthopedic system of  claim 1 , wherein the bore comprises threads adapted to engage corresponding threads on the head portion of the fastener. 
     
     
       6. The orthopedic system of  claim 1 , wherein the included angle between the reference axis and the fastener insertion axis is definable in at least two degrees of freedom. 
     
     
       7. The orthopedic system of  claim 6 , wherein the included angle between the reference axis and the fastener insertion axis is definable at any radial position about the reference axis. 
     
     
       8. The orthopedic system of  claim 1 , wherein the included angle between the reference axis and the fastener insertion axis is at least about 15 degrees. 
     
     
       9. An orthopedic system for fixation of an orthopedic plate to a bone of a patient, comprising:
 a plate body extending between an upper surface and a lower surface of the plate body; 
 an aperture extending through the plate body from the upper surface to the lower surface along a reference axis, the aperture having a sidewall extending circumferentially about an interior of the aperture; 
 a pivot member retained within the aperture, the pivot member comprising an outer surface corresponding to the sidewall, the pivot member defining a bore extending along a fastener insertion axis, wherein the pivot member is rotationally fixed in the aperture around the reference axis yet is displaceable relative to the plate body within the aperture to define an included angle between the reference axis and the fastener insertion axis; and 
 a fastener comprising an elongate portion and a head portion, wherein the elongate portion extends along the fastener insertion axis defined by the pivot member bore and the head portion is engaged with the pivot member to radially expand the pivot member to frictionally engage the sidewall with the outer surface to restrict displacement of the pivot member within the aperture relative to the plate body, 
 wherein the aperture comprises a non-circular sidewall portion and the outer surface is engageable by the non-circular portion, 
 wherein the pivot member comprises a plurality of flats extending about a perimeter of the pivot member and the non-circular sidewall has correspondingly shaped flat portions, and 
 wherein the aperture comprises a ramped surface of a flange extending relative to the aperture that engages a convex portion of the pivot member. 
 
     
     
       10. The orthopedic system of  claim 9 , wherein at least one of the bore or the head portion of the fastener disposed within the bore comprises a sloped surface such that the head portion and the bore are engageable upon receipt of the fastener in the bore to cause the pivot member to radially expand. 
     
     
       11. The orthopedic system of  claim 10 , wherein the pivot member comprises an expansion slot that allows for expansion of the pivot member radially relative to the fastener insertion axis. 
     
     
       12. The orthopedic system of  claim 11 , wherein the expansion slot extends through the entire pivot member in a direction along the fastener insertion axis. 
     
     
       13. The orthopedic system of  claim 9 , wherein the pivot member comprises chamfers extending between the plurality of flats to facilitate unrestricted pivotal movement of the pivot member relative to the plate in two degrees of freedom. 
     
     
       14. The orthopedic system of  claim 9 , wherein the bore comprises threads adapted to engage corresponding threads on the head portion of the fastener. 
     
     
       15. The orthopedic system of  claim 9 , wherein the elongate portion of the fastener is adapted to engage the bone of a patient to compressingly engage the head portion relative to the pivot member to expand the pivot member radially relative to the fastener insertion axis. 
     
     
       16. The orthopedic system of  claim 9 , wherein the included angle between the reference axis and the fastener insertion axis is definable in at least one degree of freedom. 
     
     
       17. The orthopedic system of  claim 16 , wherein the included angle between the reference axis and the fastener insertion axis is definable in at least two degrees of freedom. 
     
     
       18. The orthopedic system of  claim 17 , wherein the included angle between the reference axis and the fastener insertion axis is definable at any radial position about the reference axis. 
     
     
       19. The orthopedic system of  claim 9 , wherein the included angle between the reference axis and the fastener insertion axis is at least about 10 degrees. 
     
     
       20. The orthopedic system of  claim 9 , wherein the included angle between the reference axis and the fastener insertion axis is at least about 15 degrees.